The present invention relates to an image processing apparatus, an image forming apparatus, and an image processing method for performing a specified conversion process when filing or copying documents or images.
In an image forming apparatus, color or monochromatic images of color or monochromatic copier or the like are read, and copy images are formed, and when copying, a high image quality is required regardless of the type of the original image.
The image quality of the image information necessary to realize a high copy image quality differs significantly depending on the type of the original to be copied. For example, in the case of a photographic original, reproduction of color and gradation is important, and the image quality true to the original is demanded. On the other hand, in the case of a document original mainly containing characters, the clarity is demanded rather than the color of characters, and an easy-to-read image quality is required.
In a conventional copier, however, original modes optimizing the quality of copy image in various originals are available (character/photo mode, character mode, photo mode, map mode and the like), and the user selects a proper original mode depending on the type of the original to be copied, and copies the image. Herein, the character mode and photo mode are exclusive modes for character only and photo only, and in the case of a mixed original of character and photo, the character/photo mode is used. For example, this sort of the image forming apparatus is disclosed in U.S. patent application Ser. No. 08/682,007, in which the image processing apparatus can extinguish character area, a graph area, page area, and photo area from the image data, and it processes the image data corresponding to the extinguished areas.
However, discrimination of regions conducted by the apparatus is not always perfect in precision of discrimination, and wrong discrimination may occur, and therefore depending on the condition of image processing, the image quality may deteriorate extremely in a falsely discriminated region, or when regions of same type are discriminated differently, the image quality differs in the boundary of the two regions. To decrease problems due to such wrong discrimination, the difference in processing is reduced between the image types to be discriminated, and in the case of wrong discrimination, deterioration of image quality due to wrong discrimination may be made less obvious, but when the difference in processing between plural image types to be discriminated is reduced, the degree of improvement of image quality when discriminated correctly is smaller, and therefore the image quality when the original of characters only is, for example, formed in character/photo mode is inferior to the case when formed in character mode if discriminated correctly. Hence, more accurate discriminating capability of image types of original is demanded, and the image processing apparatus capable of processing the image accordingly is required.